As technologies of generating a gas by decomposing a fuel containing organic matters at a low temperature there are known methods and devices for generating hydrogen by electrochemical reactions, and there are also known fuel cells using hydrogen generated by such electrochemical reactions (See Patent Documents 1 to 4).    Patent Document 1: JP-B-3328993    Patent Document 2: JP-B-3360349    Patent Document 3: U.S. Pat. Nos. 6,299,744, 6,368,492, 6,432,284, and 6,533,919, and U.S. Patent Application No. 2003/0226763    Patent Document 4: JP-A-2001-297779
Patent Document 1 cited above describes (Claim 1), “a method for generating hydrogen comprising providing a pair of electrodes on the two opposite surfaces of a cation exchange membrane, contacting a fuel containing at least methanol and water with one electrode having a catalyst, applying a voltage between the pair of electrodes so that electrons are withdrawn from the electrodes thereby causing a reaction to occur on the electrodes whereby hydrogen ions are generated from methanol and water, and allowing hydrogen ions to be converted on the other electrode, being supplied with electrons, into hydrogen molecules.” The same patent document discloses another method (paragraphs [0033] to [0038]) for selectively generating hydrogen using a conversion system, the method comprising supplying water or water vapor together with methanol which serves as a fuel, applying a voltage via an external circuit to cause electrons to be withdrawn from a fuel electrode, so that reaction represented by CH3OH+2H2O→CO2+6e−+6H+ occurs on the fuel electrode, and allowing hydrogen ions thus produced to pass through a cation exchange membrane to reach the opposite electrode where the hydrogen ions undergo reaction represented by 6H++6e−→3H2. Patent Document 2 cited above describes (paragraphs [0052] to [0056]) a fuel cell which utilizes hydrogen generated by a method as described above.
According to the inventions described in Patent Document 1 (paragraph [0042]) and Patent Document 2 (paragraph [0080]) cited above, it is possible to generate hydrogen at a low temperature. However, the methods described in those inventions are obviously different from the hydrogen generating device of the present invention which will be given below in following points: those methods require the application of voltage, and hydrogen is generated on the electrode opposite to the electrode (fuel electrode) to which fuel is supplied, and no oxidizing agent is supplied to the opposite electrode.
This holds true also for the inventions disclosed by Patent Document 3 cited above similarly to Patent Documents 1 and 2 cited above. Those inventions use a system for generating hydrogen where protons generated on anode 112 serving as fuel electrode pass through partition membrane 110 to reach cathode 114 opposite to the anode, and according to the system, voltage from DC power source 120 is provided between anode (fuel electrode) and cathode (opposite electrode) to supply organic fuel such as methanol or the like to the anode 112 for electrolysis. In addition, hydrogen is generated on the electrode opposite to the fuel electrode, and no oxidizing agent is supplied to the opposite electrode.
Patent Document 4 cited above discloses a fuel cell system incorporating a hydrogen generating electrode for generating hydrogen (Claim 1). According to the disclosure of the invention, “Liquid fuel containing alcohol and water is supplied to porous electrode 1 (fuel electrode), air is supplied to gas diffusion electrode 2 (oxidizing agent-applied electrode) opposite to electrode 1, and a load is inserted between a terminal leading to porous electrode 1 and another terminal leading to gas diffusion electrode 2 to achieve electric connection allowing a positive voltage to be applied to porous electrode 1 via the load from gas diffusion electrode 2 which corresponds to the positive electrode of MEA2 capable of acting as a conventional fuel cell.” The same patent document further adds (paragraph [0007]), “As a result, alcohol reacts with water to produce carbon dioxide gas and hydrogen ion, the hydrogen ion passes through an electrolyte membrane 5 to reach a gas diffusion electrode 6 located centrally where the hydrogen ion is converted into hydrogen gas. On the opposite surface of gas diffusion electrode 6 in contact with another electrolyte layer 7, there arises another electrode reaction where hydrogen gas is reconverted into hydrogen ion, and hydrogen ions migrate through electrolyte layer 7 to reach another gas diffusion electrode 2 where hydrogen ions react with oxygen in air to produce water.” Thus, with this system, electric energy generated by a fuel cell is utilized to generate hydrogen on the hydrogen generating electrode (gas diffusion electrode 6) which is then supplied to the fuel cell. Moreover, the system is the same with those described in the patent documents 1 to 3 cited above in that hydrogen is generated on the electrode opposite to the fuel electrode.
There are some other known methods for oxidizing alcohol (methanol) (See Patent Documents 5 and 6). According to the inventions, a reaction system with a partition membrane is used where anode (electrode A) and cathode (electrode B) are placed opposite to each other with a proton conducting membrane (ion conductor) inserted therebetween, and where alcohol (methanol) is oxidized with or without concomitant application of voltage, or with concomitant uptake of electric energy. All those methods, however, are based on a method whereby alcohol is oxidized by means of an electrochemical cell (the reaction product includes carbonic diester, formalin, methyl formate, dimethoxymethane, etc.), and not on a method whereby alcohol is converted by reduction into hydrogen.”    Patent Document 5: JP-A-06-73582 (Claims 1 to 3, Paragraph [0050])    Patent Document 6: JP-A-06-73583 (Claims 1 and 8, Paragraphs [0006] and [0019])
Further, Non-Patent Documents 1 and 2 describe that in case of open-circuit and insufficient oxygen conditions for a direct methanol type fuel cell (DMFC), a galvanic reaction and an electrolytic reaction coexist in a single cell, a reaction represented by CH3OH+2H2O→CO2+6e−+6H+ occurs on the oxidizing electrode and a reaction represented by 6H++6e−→3H2 occurs on the fuel electrode, and hydrogen is generated on the fuel electrode side. However, the article of Non-patent Document 1 concludes that “the generation of hydrogen not only decreases the output of electrical power for running cells, but also continuously consumes fuel under open-circuit condition. Thus, it is important to maintain adequate and constant supply of oxygen to a cathode both the DMFC is in operation and in standby state.” The article of Non-patent Document 2 concludes that “For a DMFC having a large MEA area, attention must be given to the accumulation of hydrogen caused by shutdown and startup of the system.” Accordingly, both articles do not intend to generate hydrogen.    Non-Patent Document 1: Electrochemical and Solid-State Letters, 8(1) A52-A54 (2005)    Non-Patent Document 2: Electrochemical and Solid-State Letters, 8(4) A211-A214 (2005)
Recently, generating devices (power source devices) incorporating a fuel cell, giving consideration to environment problems, have been proposed, and when the fuel cell power generating device is used as a mobile power source or an on-site power source, a package-type fuel cell power generating device in which equipments constituting the generating device are integrated and stored in a single metal package is used in order to facilitate its transportation and installation. In this type of fuel cell power generating device, when a hydrocarbon fuel such as utility gas is used as a raw fuel, for example, a fuel reforming device for reforming it to a fuel mainly made of hydrogen is incorporated in a single package (unit case). In the package (unit case), a fuel cell itself, a power converting device for converting a direct-current power generated by the fuel cell to a power-source output specification, a control device for entire control, auxiliary machines such as a pump and a fan provided in relation with the fuel cell (See Patent Documents 7 to 11, for example).    Patent Document 7: JP-A-05-290868    Patent Document 8: JP-A-10-284105    Patent Document 9: JP-A-2002-170591    Patent Document 10: JP-A-2003-217635    Patent Document 11: JP-A-2003-297409
The fuel reforming device includes a reformer, a CO transformer, and a CO remover, and predetermined catalysts are filled in each of the equipments, and since catalysts act at a high temperature it is required to be heated. Therefore, a burner is also provided at the reformer and an original fuel is burned by the burner at start so as to raise the temperature of the catalyst in the reformer to approximately 650 to 700° C. Also, with the temperature rise of the reformer, the temperatures of the catalysts of the CO transformer and the CO remover are also gradually raised, but since the reformed gas at start is not stable, it is not supplied to the fuel cell immediately, it is fed to a PG burner to be burned before being supplied to the fuel cell (Patent Document 11, Paragraph [0003]).
On the other hand, since the control device is constituted by a large number of electronic parts, they should be protected from high heat generated by the fuel reforming device. Thus, a technology to provide an insulating bulkhead between the fuel reforming device and the control device as in Patent Documents 7 and 9, a technology for cooling the control device by forced ventilation inside the package using a blower or a ventilation fan as in Patent Documents 7 and 8, and a technology to arrange the control device so that it is not affected by heat of the fuel reforming device as in Patent Documents 10 and 11 are developed.
As mentioned above, when the conventional fuel reforming device is used, there is a problem that various devices should be used in order to prevent its thermal influence.
Also, such a package-type fuel cell power generating device not using a high-temperature fuel reforming device is known in which a cylinder filled with hydrogen storage alloy (hydrogen storage cylinder) and a fuel cell are integrated (See Patent Documents 12 and 13, for example).    Patent Document 12: JP-A-06-60894    Patent Document 13: JP-A-10-92456
The fuel cell power generating device in Patent Documents 12 and 13 does not need means for preventing thermal influence as in the case that a conventional fuel reforming device is used, but since a hydrogen emission process of the hydrogen storage alloy is a heat absorbing reaction, the temperature of the hydrogen storage alloy is lowered when a hydrogen fuel is supplied, and since a hydrogen emitting capability of the hydrogen storage alloy is lowered with lowering of the temperature, it is necessary to heat the hydrogen storage alloy by guiding a generated heat at the fuel cell itself to a hydrogen storage cylinder in order to ensure a sufficient hydrogen flow rate, and also there is a problem that a generating time is limited since the cylinder is used.
Moreover, an electric automobile provided with a fuel cell as a power source to obtain the driving power is known on which methanol or the like is loaded as a raw fuel as well as a reformer for reforming the raw fuel to perform a reforming reaction for generating a gas containing hydrogen is loaded (See Patent Documents 14 to 17, for example). When liquid fuel such as methanol is particularly used as a raw fuel, such an electric automobile loading the raw fuel and the reformer thereon has a merit that a travel distance which can be covered by the electric automobile by one fuel replenishment is longer than a case where a gas fuel is loaded. Moreover, the raw fuel such as methanol or hydrocarbon has a merit that it is easily and safely handled at the time of transportation as compared with hydrogen gas.    Patent Document 14: JP-A-2000-149974    Patent Document 15; JP-A-2001-113960    Patent Document 16: JP-A-2001-202980    Patent Document 17: JP-A-2001-298807
However, with regard to a reformer in the case where methanol, dimethyl ether (DME), ethanol, natural gas, propane, gasoline, etc. is loaded on an electric automobile as a raw fuel, development of a methanol reformer with the lowest reforming temperature is most advanced, and currently, three reforming methods are employed therefor: steam reforming, partial oxidation reforming and combined use of the both (See Non-patent Document 3). However, any of the reforming methods require reforming performed at a high temperature of 200° C. or more in order to manufacture gas containing hydrogen, and there are problems of poisoning of a reforming catalyst, removal of CO contained in the reformed gas (gas containing hydrogen), mixing of nitrogen in the air into the reformed gas obtained by partial oxidation reforming or combined reforming.    Non-Patent Document 3: “Development and Practical Application of Solid Polymer Type Fuel Cell”, pp. 141 to 166, May 28, 1999, issued by Technical information Institute, Co., Ltd.
On the other hand, there has been developed an electric automobile (fuel cell automobile) incorporating a container which stores hydrogen in the form of hydrogen gas or a hydrogen storage alloy. However, a major problem in expanding use of this electric automobile is improvement of hydrogen supply infrastructure. That is, there is a problem of how to improve the hydrogen supply infrastructure of wide-area for fuel cell automobiles that run freely. Thus, due to the merit of being capable of utilizing the existing infrastructures such as utility gas grids, gas stations and the like, systems for subjecting utility gas or liquid fuel (desulfurized naphtha, gasoline, kerosene, light oil, methanol or the like) to steam reforming by a reformer at a hydrogen supply station to generate hydrogen, storing the generated hydrogen in a hydrogen storage tank and supplying the hydrogen to a hydrogen storage container in a fuel cell automobile are most developed (See Patent Documents 18 to 21, for example).
However, the above-described hydrogen supply systems have problems that the reforming device is expensive, has a large device size and is accompanied by complicated maintenance and operation of device requiring sophisticated skills.    Patent Document 18: JP-A-2002-315111    Patent Document 19: JP-A-2002-337999    Patent Document 20: JP-A-2003-118548    Patent Document 21: JP-A-2004-79262
There have also been developed systems for generating hydrogen by electrolyzing water, storing the generated hydrogen in a hydrogen storage tank and supplying this hydrogen to a hydrogen storage container in a fuel cell automobile instead of reforming a fuel containing organic matters as described above (See Patent Documents 22 and 23, for example).
These systems require no such high temperature for reforming a fuel containing organic matters, however, they have a problem of requiring a large amount of electric power.    Patent Document 22: JP-A-2002-161998    Patent Document 23: JP-A-2002-363779
In a conventional submergible ship provided with a fuel cell as a power source to obtain the driving force, a method for storing hydrogen in the form of high-pressure hydrogen gas and supplying the hydrogen to the fuel cell is generally employed (See Patent Documents 24 to 26, for example). In this method, the gas container must be pressure-resistant, and therefore, the mass of the container becomes larger. When a submergible ship is heavy in weight, floating buoyant materials corresponding to the increased weight are required. Consequently, there occurs a problem that the submergible ship becomes larger due to the provision of the floating buoyant materials. Moreover, since hydrogen is stored in the form of a high-pressure gas, there is also a problem that attention must be paid to safety and handling of hydrogen is difficult.    Patent Document 24: JP-A-10-100990    Patent Document 25: JP-A-10-144327    Patent Document 26: JP-A-10-181685
To solve the above-described problems, there has been developed “a hydrogen generating device for submergible machine (including submergible ship) which generates hydrogen by bringing a metal hydroxide (including a complex metal hydroxide) into contact with a hydrogen generation accelerator among hydrogen supply and generation devices used as a power source of a submergible machine, characterized in that at least one of the metal hydroxide and the hydrogen generation accelerator is liquid, a container in which the liquid metal hydroxide or liquid hydrogen generation accelerator is stored is arranged in the submergible machine, and the pressure in the container is substantially equalized with the water pressure outside the machine” (See Patent Document 27). Although the metal hydroxide used in this hydrogen generating device can be handled easier than high-pressure hydrogen gas, it has a strong reactivity different from fuel containing organic matters as a hydrogen raw material. Thus, measures are required for preventing contact with water or alcohol that is a hydrogen generation accelerator and reaction control is difficult.    Patent Document 27: JP-A-2002-187595
It is also known that a reformer which reforms a hydrocarbon fuel to generate hydrogen is mounted on a submersible machine and the hydrogen generated by the reformer is supplied to a fuel cell (See Patent Document 28, for example). In this case, however, there are problems similar to those in the above-described electric automobile.    Patent Document 28; JP-A-08-17456